Reince Priebus (pictured) is being sought for questioning by special prosecutor Robert Mueller

US special prosecutor Robert Mueller is seeking to interview former White House chief of staff Reince Priebus as apart of a ever widening investigation into the Trump administration.

According to the New York Times, Mueller's office is currently in contact with the White House about interviewing former and current senior staff at 1600 Pennsylvania Avenue.

Mueller is looking to speak to officials who may provide information, transcripts, notes and testimony on a number of issues, including insight on President Donald Trump's decision to fire former FBI Director James Comey in May.

Mueller is also looking to attain information from senior Trump officials related to possible Russian interference in the 2016 election

White House Chief of Staff Reince Priebus arrives for an event where US President Donald Trump will present the Medal of Valor to the first responders of the June 14 shooting against members of the Republican Congressional Baseball team

Indications that Mueller's investigation is intensifying was evident last week when he executed a warrant to search the Alexandria, Va., home of Paul Manafort, Trump’s former campaign chairman.

A lawyer for Trump, John Dowd, described the warrant as excessive, and accused Mueller of abusing his position of power.

'The search warrant here was obtained by a gross abuse of the judicial process by the special counsel’s office,' Dowd in an email to The Wall Street Journal.

'In addition, given the obvious unlawful deficiencies, this extraordinary invasive tool was employed for its shock value to try to intimidate Mr. Manafort,' he added

Priebus did not respond to a request for comment by the Times.

At least three sources with law enforcement told the New York Times that the White House and Mueller (pictured) are in communication

A special legal adviser to Trump, Ty Cobb, said the White House would 'continue to fully cooperate' with the Mueller investigation.

The Times notes that figures close to the administration are concerned with Mueller's probing into Priebus, who was chair of the Republican National Committee and worked closely with the Trump campaign during the election.

After the election, Priebus was made chief of staff and worked directly with the President on key decisions made in the first six months of the administration, until late last month when he was ousted from the position.

Priebus also reportedly spoke to Comey on February 8, a week before Trump allegedly asked the former FBI director to drop an investigation into the president's former National Security Director Michael Flynn, according to a law enforcement official briefed on the matter.

The law enforcement official told the Times that Comey discussed with Priebus a Justice Department policy that bars White House officials from speaking with the FBI about ongoing investigations to avoid the appearance of impropriety or political meddling.

It remains unknown if Priebus relayed the information to Trump.

Mueller's probe is showing signs of widening with last week's issuing of a search warrant at the home of former Trump campaign chairman Paul Manafort (pictured)

The FBI began looking into the possibility of Russia attempting to meddle in the election around July 2016 (pictured: Russian President Vladimir Putin)

Trump denies having a private meeting with Comey or asking him to end the investigation into Flynn.

Comey testified to Congress earlier this year that Priebus was aware of the one-on-one encounter he and the President had on February 14. Comey also testified that Trump ordered the Vice President, senior administration officials and Priebus to leave the Oval Office after a national security briefing.

'The president began by saying Flynn hadn’t done anything wrong in speaking with the Russians, but he had to let him go because he had misled the vice president,' Comey told Congress during a public hearing in June.

'The president then made a long series of comments about the problem with leaks of classified information — a concern I shared and still share. After he had spoken for a few minutes about leaks, Reince Priebus leaned in through the door by the grandfather clock and I could see a group of people waiting behind him. The president waved at him to close the door, saying he would be done shortly. The door closed.'

After the door closed, Comey said that was when Trump asked him to end the investigation into Flynn.

Mueller is also investigating allegations that the Russian government interfered with the 2016 presidential election to sway the vote into Trump's favor.